Maybe some of the stall pundits here can shed light on the following.
My aircraft stalls at 31 mph IAS at max weight, the book figure is 35 mph "in level flight". The ASI has recently been checked and found accurate.
Recently on a near-windless day I thought I would check this against the GPS, out of curiosity. So I went up to altitude (2900 ft density altitude), near max weight and middling CofG, slowed gently and stalled on a downwind heading, then upwind, then 90 deg each side. To my surprise and puzzlement the GPS speed in each case was 54-55 mph with little variation.
I do not know whether the GPS figure will include the vertical speed component, which I reckoned was about 500 fpm (= 6 mph) at the stall.
Has anyone else here tried this?